[R-390] R390A to R725 conversion question

[Tom M.]

Wally was a good guy. I had many good chats with him about engineering and his BA experience. I still have all the letters he sent me. 


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On Wednesday, October 30, 2024, 8:09 PM, Les Locklear <leslocklear at hotmail.com> wrote:

Yeah, Tom is right on that, Wally Chambers K5OP was the "Mr. R390A" that Dallas Lankford regularly referred to in his notes and modifications. He was a good friend and regularly visited to attend the local hamfests when there still had them on the Mississippi Gulf Coast. I owned an Arvin (serial No. 95), a modified 1967 EAC s/n 7857 and that is what I remembered from owning it. 
 
Les Locklear
 


----- Original Message -----
From: Tom M. via R-390 <r-390 at mailman.qth.net>
Reply-To: Tom M. <courir26 at yahoo.com>
To: r-390 at mailman <r-390 at mailman.qth.net>, Perry Sandeen <sandeenpa at yahoo.com>
Sent: 10/30/2024 7:38:08 PM
Subject: Re: [R-390] R390A to R725 conversion question
________________________________________________________________________________

>  Perry,
> The added transformer in the R-725 was for PTO hum bucking, not filaments. sk 
> Wally Chambers informed me of that fact.
> 
> The R-725 had the rewired R-390 filaments.  I've done this myself and wrote a procedure how to do it. I agree with you it was a bit of a PITA.
> I use the converted IF deck in my daily driver R-390A to this day.
> Tom
> 
> 
> 
> 
>    On Wednesday, October 30, 2024 at 04:31:35 PM CDT, Perry Sandeen via R-390 
> <r-390 at mailman.qth.net> wrote:  
>  
>  List,
> IIRC I've seen 3 published articles for r390a to r725 conversion all using the re-wiring of the R390 IF to 6 volt filaments.  This seems to be a big PITA.
> When the military did the original they just added another 26 volt filament 
> xformer. This seems a much easier approach especially when we have small SRPS's available.
> 
> If anyone would have the schematics or TM addendum I would appreciate it if 
> they would contact me off list.
> TIA
> Perry
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